Asus CM1831-US-3AB Desktop PC for $519.99 shipped after a $30 rebate.  Here is a screenshot for your reference.  It features an AMD 8-core Bulldozer FX8120 CPU at 3.1GHz, 8GB DDR3 RAM, 1TB hard drive, 802.11b/g/n wireless, gigabit ethernet, dual layer DVD burner, Windows 7 Home Premium (64-bit), and more.  Most places have it for about $700.